Intermediate Algebra (6th Edition)

Published by Pearson
ISBN 10: 0321785045
ISBN 13: 978-0-32178-504-6

Chapter 8 - Section 8.1 - Solving Quadratic Equations by Completing the Square - Exercise Set - Page 485: 56

Answer

$x=\left\{ -1,\dfrac{2}{5} \right\}$

Work Step by Step

Using the completing the square method, the solutions of the given quadratic equation, $ 5x^2+3x-2=0 ,$ is \begin{array}{l}\require{cancel} \dfrac{1}{5}\cdot(5x^2+3x-2)=(0)\cdot\dfrac{1}{5} \\\\ x^2+\dfrac{3}{5}x-\dfrac{2}{5}=0 \\\\ x^2+\dfrac{3}{5}x=\dfrac{2}{5} \\\\ x^2+\dfrac{3}{5}x+\left( \dfrac{3}{5\cdot2}\right)^2=\dfrac{2}{5}+\left( \dfrac{3}{5\cdot2}\right)^2 \\\\ x^2+\dfrac{3}{5}x+\dfrac{9}{100}=\dfrac{2}{5}+\dfrac{9}{100} \\\\ x^2+\dfrac{3}{5}x+\dfrac{9}{100}=\dfrac{40}{100}+\dfrac{9}{100} \\\\ \left( x+\dfrac{3}{10}\right)^2=\dfrac{49}{100} \\\\ x+\dfrac{3}{10}=\pm\sqrt{\dfrac{49}{100}} \\\\ x+\dfrac{3}{10}=\pm\dfrac{7}{10} \\\\ x=-\dfrac{3}{10}\pm\dfrac{7}{10} \\\\ x=-\dfrac{3}{10}-\dfrac{7}{10} \\\\ x=-\dfrac{10}{10} \\\\ x=-1 ,\\\\\text{OR}\\\\ x=-\dfrac{3}{10}+\dfrac{7}{10} \\\\ x=\dfrac{4}{10} \\\\ x=\dfrac{2}{5} .\end{array} Hence, $ x=\left\{ -1,\dfrac{2}{5} \right\} .$
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.